Classification criteria for diffuse idiopathic skeletal hyperostosis: a lack of consensus

Objectives. DISH is a condition characterized by flowing ossifications of the spine with or without ossifications of entheses elsewhere in the body. Studies on the prevalence and pathogenesis of DISH use a variety of partly overlapping combinations of classification criteria, making meaningful comparisons across the literature difficult. The aim of this study was to systematically summarize the available criteria to support the development of a more uniform set of diagnostic/classification criteria. Methods. A search was performed in Pubmed, Embase, Cochrane Library and Web of Science using the term DISH and its synonyms. Articles were included when two independent observers agreed that the articles proposed a new set of classification criteria for DISH. All retrieved articles were evaluated for methodological quality, and the presented criteria were extracted. Results. A total of 24 articles met the inclusion criteria. In all articles, spinal hyperostosis was required for the diagnosis of DISH. Peripheral, extraspinal manifestations were included as a (co-)requirement for the diagnosis DISH in five articles. Most discrepancies revolved around the threshold for the number of vertebral bodies affected and to defining different developmental phases of DISH. More than half of the retrieved articles described a dichotomous set of criteria and did not consider the progressive character of DISH. Conclusion. This systematic review summarizes the available different classification criteria for DISH, which highlights the lack of consensus on the diagnosis of (early) DISH. Consensus criteria, including consecutive phases of new bone formation that characterize DISH, can be developed based upon established diagnostic/classification criteria.